Update download-data to download necessary data for futures

freqtrade/exchange/exchange.py

@@ -1326,7 +1326,6 @@ class Exchange:
         :param candle_type: '', mark, index, premiumIndex, or funding_rate
         :return: List with candle (OHLCV) data
         """
-        data: List
         pair, _, _, data = asyncio.get_event_loop().run_until_complete(
             self._async_get_historic_ohlcv(pair=pair, timeframe=timeframe,
                                            since_ms=since_ms, is_new_pair=is_new_pair,
@@ -1494,7 +1493,7 @@ class Exchange:
                 pair, timeframe, since_ms, s
             )
             params = deepcopy(self._ft_has.get('ohlcv_params', {}))
-            if candle_type:
+            if candle_type not in (CandleType.SPOT, CandleType.SPOT_):
                 params.update({'price': candle_type})
             data = await self._api_async.fetch_ohlcv(pair, timeframe=timeframe,
                                                      since=since_ms,